Various types of image scanning lenses used in image scanning devices, such as facsimile machines and image scanners, are known. For example, Japanese Laid-Open Patent Application H11-190820, Japanese Laid-Open Patent Application 2000-249913, and Japanese Laid-Open Patent Application 2002-31753 disclose such image scanning lenses. The image scanning lenses described in these three Japanese applications include four lens components, with each lens component being a lens element, and the described image scanning lenses are designed to have high resolution corresponding to the high density of image detecting elements used in the CCD's that are used as image pickup elements in the image scanning devices.
However, today high optical performance related to scanning color images is demanded. The image scanning lenses of the Japanese applications discussed above have problems of chromatic aberrations that result in these lenses not always providing satisfactory performance for high precision color images.